diff --git a/src/apps/common/ns_turn_utils.c b/src/apps/common/ns_turn_utils.c
index 501ded0f..bc25d0db 100644
--- a/src/apps/common/ns_turn_utils.c
+++ b/src/apps/common/ns_turn_utils.c
@@ -861,21 +861,23 @@ char *turn_strdup_func(const char* s, const char* function, int line) {
 
 ////////////////////////////////
 
-int secure_username(u08bits *username)
+int is_secure_username(const u08bits *username)
 {
-	int ret = -1;
+	int ret = 0;
 	if(username) {
-		unsigned char *s = (unsigned char*)turn_strdup((char*)username);
+		unsigned char *s0 = (unsigned char*)turn_strdup((const char*)username);
+		unsigned char *s = s0;
 		while(*s) {
 			*s = (unsigned char)tolower((int)*s);
 			++s;
 		}
-		if(strstr((char*)s," ")||strstr((char*)s,"\t")||strstr((char*)s,"'")) {
-			username[0]=0;
-		} else if(strstr((char*)s,"and")&&strstr((char*)s,"union")&&strstr((char*)s,"select")) {
-			username[0]=0;
+		s = s0;
+		if(strstr((char*)s," ")||strstr((char*)s,"\t")||strstr((char*)s,"'")||strstr((char*)s,"\"")||strstr((char*)s,"\n")||strstr((char*)s,"\r")||strstr((char*)s,"\\")) {
+			;
+		} else if(strstr((char*)s,"union")&&strstr((char*)s,"select")) {
+			;
 		} else {
-			ret = 0;
+			ret = 1;
 		}
 		turn_free(s,strlen((char*)s));
 	}
@@ -883,3 +885,4 @@ int secure_username(u08bits *username)
 }
 
 //////////////////////////////////////////////////////////////////
+
diff --git a/src/apps/common/ns_turn_utils.h b/src/apps/common/ns_turn_utils.h
index 9deec287..809a04c4 100644
--- a/src/apps/common/ns_turn_utils.h
+++ b/src/apps/common/ns_turn_utils.h
@@ -78,7 +78,7 @@ void rollover_logfile(void);
 
 ///////////////////////////////////////////////////////
 
-int secure_username(u08bits *username);
+int is_secure_username(const u08bits *username);
 
 ///////////////////////////////////////////////////////
 
diff --git a/src/apps/relay/mainrelay.c b/src/apps/relay/mainrelay.c
index f0c64d87..66326757 100644
--- a/src/apps/relay/mainrelay.c
+++ b/src/apps/relay/mainrelay.c
@@ -1536,6 +1536,10 @@ static int adminmain(int argc, char **argv)
 #endif
 		case 'u':
 			STRCPY(user,optarg);
+			if(!is_secure_username((u08bits*)user)) {
+				TURN_LOG_FUNC(TURN_LOG_LEVEL_ERROR, "Wrong user name structure or symbols, choose another name: %s\n",user);
+				exit(-1);
+			}
 			if(SASLprep((u08bits*)user)<0) {
 				TURN_LOG_FUNC(TURN_LOG_LEVEL_ERROR, "Wrong user name: %s\n",user);
 				exit(-1);
diff --git a/src/server/ns_turn_server.c b/src/server/ns_turn_server.c
index b3d9e5dd..3db0aeef 100644
--- a/src/server/ns_turn_server.c
+++ b/src/server/ns_turn_server.c
@@ -1015,7 +1015,9 @@ static int handle_turn_allocate(turn_turnserver *server,
 					}
 					ns_bcopy(value,username,ulen);
 					username[ulen]=0;
-					if(secure_username(username)<0) {
+					if(!is_secure_username(username)) {
+						TURN_LOG_FUNC(TURN_LOG_LEVEL_ERROR, "%s: wrong username: %s\n", __FUNCTION__, (char*)username);
+						username[0]=0;
 						*err_code = 400;
 						break;
 					}
@@ -3342,7 +3344,9 @@ static int check_stun_auth(turn_turnserver *server,
 	ns_bcopy(stun_attr_get_value(sar),usname,alen);
 	usname[alen]=0;
 
-	if(secure_username(usname)<0) {
+	if(!is_secure_username(usname)) {
+		TURN_LOG_FUNC(TURN_LOG_LEVEL_ERROR, "%s: wrong username: %s\n", __FUNCTION__, (char*)usname);
+		usname[0]=0;
 		*err_code = 400;
 		return -1;
 	} else if(ss->username[0]) {